Are ovulation calendars accurate?

“ovulation calendar is saying my ovulation date is may12 i had sex on may 8 and 9 what are my chances of being pregnant. And are these calendar correct on ovulation times.”

A: “The accuracy of an ovulation calendar depends on how long a woman’s cycle is. Some women have 28 day cycles, other women’s cycles may be longer or shorter. This makes it difficult to predict ovulation because standardized calendars don’t always reflect everyone’s cycle. Also, sperm can live 5-7 days in a woman’s body, so if someone has unprotected sex around ovulation, there is a possiblity for pregnancy. To prevent pregancy, be sure to use a method of birth control everytime you have sex. If you have more questions about tracking your ovulation be sure to consult with your doctor.”